Signal translating apparatus



3 Sheqts-Sheet 1 FIG. 2 TM F. GRAY SIGNAL TRANSLATING APPARATUS FiledFeb. 11, 1939 STATION 8 SYNCHRON- J IZER STATION A July 29, 1941.

FIG. 3

FIG. 3

58' FIG. 5

MULT/PLEXED SIGNAL ATTORNEY INVENTOR E GRAY v Okdztu QM F. GRAY SIGNALTRANSLATING APPARAIfUS Jul 29, 1941.

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F. GRAY ATTORNEY July 29, 1941.

3 Sheets-Sheet 3 Filed Feb. 11, 1939 FIG. /3

, qa wflfiwhwat to; V V qwxuqmkfit qwxuisat R v E #5: 1 vim; 4 A N435x35 k D M 8 1 a g m WE A 6 r W B w 8 a a M 3 m I a I 6 u 35E c 382w F#3355 54 FIG. I? a Patented July 29, 1941 'S Es 1 I "ISIGNALTalnzfifiemmm Telephone Laboratories, Incorporated, York, N. Y., acorporation of New Yorkv Application February 11, 1939, Serial No.255,897

13 Claims. (Cl. 250-152) This invention relates to signal translatingapparatus and more particularly to multiplex telephone systems andelectronic distributors or commutators therefor.

In general, in multiplex telephone systems, a plurality of complexsignals or electrical waves, corresponding, for example, to speech ormusic, are produced at individual sending stations, commutated at acommon transmitter and transmitted together with a carrier to areceiver. At the receiver, the signals corresponding to the originalcomplex signals or waves are separated and distributed to individualstations.

In such systems, faithful and satisfactory translation of the originalsignals or waves neces- The operation of theisystem comprises, broadlyspeaking, the repeated sampling .of' the complex signals produced at theindividual channels connected to the transmitter, transmission of'thesamples, and then the distribution of the complex signals to thecorresponding individual channels at the receiver. The-sampling isrepeated so frequently that the; original signals are reproducedsubstantially in their original form sitates the reproduction ateach ofthe individual receiving stations a complex wave corresponding in time,frequency and magnitude to the waves or signals produced at thecorresponding sending station. It necessitates alsosubstantiallycomplete segregation at the receiver of the several complexsignals or waves so that there will be no distortion of the sound ormusic distributed to the individual receiving stations and the signalreceived at each of the latter will correspond accurately to theoriginalsignal produced at the corresponding sending station, withoutnoise or cross-talk effects,

One object of this inventionis to faithfully commutate and thendistribute a plurality of complex signals or waves.

Another object of this invention is to prevent distortion, as bycross-talk, of the complex distributed signals or waves.

A further object of this invention is to simplify multiplex telephonesystems and the commutators and distributors utilized therein.

Still another object of this invention is to eliminate cross-talk inmultiplextelephone systems in a facile and economic manner.

In one illustrative embodiment of this invention, a multiplex telephonesystem comprises a transmitter anda receiver connected by a commontransmission channel, the transmitter and receiver having connectedthereto a plurality'of individual translatingor signal channels. The

common transmission channel is. connected to the individual channels insuccession-and repeatedly at high frequency, at both the receiver andtransmitter, by a commutator or distributor, the commutators ordistributors at the receiver and transniitter being in synchronismwhereby only corresponding, individual channels at opposite .ends of thecommon transmission channel are connected'at any particular instant,

. sequence and repeatedly atlhighfrequencyi In accordance withonefeature of this invention, the targets or plates have thesurfacesthereof upon which the electron beam impinges constructed or treated sothat they are capable of efficient and copious secondaryelectronemission. These targets or plates are cooperatively associated witha-common-collector electrode or anode which maybe connected to thecommon transmission channel, q

In accordance with :another feature of this invention, the electrongunandthe beam deflecting electrodes :are asso'ciated'to" constitute anelectron lens'system having a 'point'iccus within the electron gun andcapableof projecting upon the targets or "plates a sharply defined imageof thefocus'point. i I

In accordance 'with a further feature of this, invention, a shielding'imen'iber'is provided adjacent the targets or plates to preventdispersion of electrons which do not'fimpinge upon the targets orplates, and to prevent-alsoimpinge- .ment of such-electrons uponoth'erportions of the trajectoryof the electronbeam.-

-- In accordance-with another featu'r 5 or this invention, an *auxiliaryelectrode is provided in cooperative relation with theplatesf or tarets, which eiectrode functions to reducethe capacitances between theplates 01* targets and the collector electrode or anode'and'may 'beutilized also to, controlor modulate the secondary electron currents tothe; collector' electrodel' In accordance with still another feature ofthis invention, each of the targets or plates may constitute a primarycathode of an electron multiplier having the common collector electrodeor anode as the output electrode.

The invention and the foregoing and other features thereof will beunderstood more clearly and fully from the following detaileddescription with reference to the accompanying drawings wherein:

Fig. 1 is a schematic diagram of a multiplex signaling system showinggenerally the components of a system illustrative of one embodiment ofthis invention;

Fig. 2 is another shematic diagram showing generally elements of anelectronic distributor device forming a component of the systemillustrated in Fig. 1;

Fig. 3 is a view in perspective of an electron beam distributorconstructed in accordance with this invention, a portion of theenclosing vessel being broken away to show the internal structures moreclearly;

Fig. 4 is a detail view in section of the electron gun and electron lenssystem incorporated in the distributor shown in Fig. 3.

Figs. 5 and 6 are partial cross-sectional views along planes 5-5 and6-6, respectively, of Fig. 3 illustrating the form of the backing plateand targets, respectively, in the distributor shown in Fig. 3 andshowing also the space relation of the targets with respect to oneanother and the collector electrode;

Fig. 7 is a circuit diagram illustrating the use of the distributorshown in Fig. 3 as a sending or transmitting device;

Fig. 8 is another circuit diagram illustrating the use of thedistributor shown in Fig. 3 as a receiving device;

Fig. 9 is a schematic viewillustrating the lens equivalent of thestructure shown in Fig. 4;

Fig. 10 is a perspective view of an electron beam distributorillustrative of another embodiment of this invention. a Portion of theenclosing vessel being broken away to show the internal structures moreclearly;

Fig. 11 is a side view of the distributor shown in Fig. 10, partlybroken away and partly in section along plane ll-ll of Fig. 10;

Fig. 12 is a perspective view of an electron beam distributorillustrative of still another embodiment of this invention, a portion ofthe enclosing vessel and of one of the electrodes being broken away toshow details more clearly;

Fig. 13 is an enlarged detail perspective view of the target end of thedistributor illustrated in Fig. 12, a portion of the shield being brokenaway to show the targets and the supports therefor more clearly;

Fig. 14 is a side view in section along plane il-ll' of Fig. 13;

Figs. 15 and 16 are circuit diagrams illustrating the use ofdistributors of the construction shown in Figs. 12, 13 and 14 in two-wayconversation systems; and

Fig. 1'7 is a schematic detail view illustrating a modification of anelectron beam distributor constructed in accordance with this invention.

Referring now to the drawings, the multiplex transmission systemillustrated schematically in Fig. 1 comprises a common transmissionchannel 20 connected to the two stations A and B. For purposes ofdiscussion station A will be treated as a transmitting station andstation B as will be apparent from the description appearinghereinafter, each station may be utilized for both transmission andreception. Station A comprises a commutator or distributor having aplurality of segments a to f, inclusive, and a rotatable means or arm 2|for connecting each of. the segments to the common channel 2!. Suitablechannels 22, for example telephone lines, are connected individually tothe segments. The receiving station 3 likewise comprises a commutator ordistributor having a rotatable means or arm 2| and a plurality ofsegments a to f, inclusive, which are connected individually to channels22, for example telephone lines. The rotatable connecting means 2| and2| are connected through a synchronous system 23 so that when the arm 2|connects the common channel 20 to one of the segments at station A, thearm 2l' connects the corresponding segment at station B to the commonchannel 20.

Signals, such as complex electrical waves corresponding to speech ormusic, impressed upon the channels 22 are sampled and commutated atstation A and transmitted substantially simultaneously over the commontransmission channel 20. At station B, the multiplex signal from thecommon channel is analyzed and the individual signals distributed to theproper segment a to j and the associated individual channels 22'.

The frequency of sampling and distributing will be dependent, of course,upon the requirements of each particular system. For commercialtransmission of speech, it has been found that transmission offrequencies up to about 3,000 cycles is satisfactory. For suchtransmission, 9. frequency of about 6,000 cycles for sampling anddistributing is indicated to be adequate. with such a distributorfrequency, p ech components above 3,000 cycles will beat with thedistributor frequency to produce frequencies of less than 3,000 cycles.In order to eliminate the spuriousirequencies thus produced and therebyto obtain faithful transmission and reproduction of the originalsignals, each of the individual channels may be designed in accordancewith known methodsto have a cut-off frequency of about 3,000 cycles.

The multiplexed signal transmitted over the common channel 20 willcomprise a series of square-topped waves. For economic and practicalreasons, the frequency range of the common channel is terminated at acut-off frequency, which may be designated as fc. This may result in thespreading out of an impulse at one of the segments a to I and anoverlapping thereof upon an impulse from the next adjacent segment witha consequent cross-talk between the individual channels.

Such cross-talk may be substantially eliminated, or at least held toamplitude levels not objectionable for commercial speech transmission ifthe cut-011' frequency In is approximately or greater than l/T, where Tis the time interval between the centers of the impulses. If there are nindividual speech channels each having a cutoff of 3,000 cycles, theupper frequency limit required for the common channel is determinable bythe relation ,fc=7l-X 6000.

Each of the distributors, as shown schematically in Fig. 2, comprisesmeans, to be described fully hereinafter, for producing a rotatingconcentrated electron beam E, which impinges in succession upon thesegments 3, four of which will be treated as a receiving station,although, only are shown in Fig. 2, and a collector elecmay impingesconstructed or treated to render .it

capable of copious and emcient secondary elecv tron emission.

At the sending station A, the various segments '3 was nuts 40 hasconnected thereto a leading-in conductor encased in an insulatingsleeve", such as a have applied thereto variable potentialscorresponding to the signal, for example, speech or music, to betransmitted. The electron beam in impinging upon a segment will causethe. emission of secondary electrons and the flow of a current from thesegment to the collector electrode K, the magnitude of the current beingde-.

termined by the potential upon the segment. As the beam rotates, thesecondary electron currents from the segments in succession flow to thecollector electrode and together produce a multiplex signal which istransmitted over the common channel 25.

- At the receiving station B, the electron beam E is modulated inaccordance with the incoming multiplex signal, designated by the line Min Fig. 2, in a manner to be described hereinafter. As the beam rotatesit impinges upon the segments in sequence and causes the emission ofsecondary electrons therefrom, which flow to the collector K.Corresponding speech or music signals, then, may be distributed toindividual receiving or listening stations each connected be tween thecollector K and one of the segments by means including the channels 22.Inasmuch as the beams are rotated in synchronism, each segment at thereceiving'station will be connected effectively only to thecorresponding seg- .ment at the sending or transmitting station.

One illustrative electron beam distributor or commutator constructed inaccordance with this invention comprises, as shown in Fig. 3, anelongated enclosing vessel having aligned inwardly extending stems 3|and 32 at opposite ends thereof. Mounted upon the stem 3|, as bysupports including a plurality of uprights or standards 33 aflixed toand extending from bands or collars 34 clamped about the stem 3|, is anelectron beam producing and beam rotating structure. This structure, asshown more clearly in Fig. 4 comprises a thermionic cathode 35 supportedfrom the stem 3| by leading-in conductors 35 embedded in the stem. Inthe form illus-- trated in Figs. 3 and 4 the cathode is of theindirectly heated equipotential type, although it will be understoodthat cathodes of other types, for example, filamentary, may be used. Thecathode 35 is encompassed by a cylindrical electrode 31 which isprovided with a leading-in conductor 38 and is aflixed 'to an insulatingspacer vided with a leading-in conductor 46. Prefer ably, the electrode44 is coaxial with the cathode 35 and the bore therein is circular,although the bore may be of other section, for example rectangular orelliptical. or i The flange or disc '43 has secured thereto a pluralityof metallic supports 41, such as rods glass tube, fitted in an aperturein the discorflange 33. The rods or supports 41. carry pairs of similardeflector or sweep plates 53 and. II which are equally spaced about an'axis coincident with the longitudinal axis of the electrode 44. Asshown clearly in Fig. 3, each of the deflector or sweep plates has arectangular portion aflixed to one of the supports 41 and an outwardlybent trapezoidal portion. The rectangular portions form an enclosureinto which the electrode 44 extends.

The electrode 31 acts as an electron lens L1, as illustrated in Fig. 9,to produce a point focus P just inside the lower end of the electrode44, which acts as a first anode. This anode together with the sweep ordeflector plates 50 and 5|, which act as a second anode, define a secondelectron lens I4 producing a second focus whereby an image of the pointP is produced at the point P1.

A cup-shaped or cylindrical collector electrode or anode 52, coaxialwith the anode 44, is supported from the stem 32 by a rigid leading-inconductor 53 sealed in this stem. Equally spaced about the collectorelectrode 52 and arranged coplanar and in circular formation, as. shownclearly in Fig. 6, are a plurality of platesor targets 54, which may besubstantially sectoral as shown. Preferable, the platesor targets 54'are constructed of a material which will result in the emission of aplurality of secondary electrons for each impinging primary electronwhereby an amplification of the impinging electron beam individually toand support the targets or plates 54. Disposed behind the targets orplates 54 is an annular plate or electrode 51 which is supported by rodsor wires 5 8 extending from a collar or band clamped about the stem 32and having a leading-in conductor 59 connected thereto. This plate orelectrode 51 receives electrons which do not impinge upon the targets orplates 54 and shields the various leading-in conductors extending fromthe stem 32 from such electrons. Preferably, the surface of the plate orelectrode 51 is coated with a fluorescent material to facilitateadjustment of the electron beam.

The device shown in Fig. 3 may be operated either as a sendingdistributor, as illustrated in Fig. 7, or as a receiving distributor asillustrated in Fig. 8. As shown in Fig. 7, the cathode heater, which maybe a filament 50, is supplied from a suitable source such as a batteryGI and the of 600 volts, with respect to the cathode asby a battery 53,the sweep or deflector plates '50 and 5| being connected to anintermediate positive point of this battery through the secondarywindings of transformers 64 and 6 5. The positive potential applied tothese plates may be'of the order of 300 volts.

The sweep or deflector plates 50 and 5| are aded thereon, each or whichenergized at high frequency, for example 6,000

cycles, by oscillators 55 and 51, respectively, through the transformers54 and 55, the two is connected between the cathode and controlelectrode of a corresponding amplifier II. The output circuit of eachamplifier is coupled to a corresponding output or receiving channel 22'.

by rotating the external sweep coils aboutthe channels 22 through atransformer 58 and the.

collector electrode or anode 52 is connectedto a point common to thesecondary .windings of all the transformers 58, through a suitableresistance l5 and a source, such as a battery III, which maintains thecollector electrode or anode at a positive potential with respect toeach of the targets or plates. When the device is utilized as a sendingdistributor, this potential referably is such that it alone would drawabout one-half of the secondary electrons, for no signal, away from eachtarget or plate so that the collector electrode operates aboutsubstantially the midpoint of the secondary current-potential betweentargets and collector characteristic.

The resistance 69 is connected across the input circuit of an amplifierII, a suitable blocking condenser I2 being provided-as shown. The outputcircuit of the amplifier is coupled to the common transmission channel20.

The electrons emanating from the cathode 35 are concentrated into a beamfocussed, as described heretofore, to a point P1, which, when the beamis rotated by the fields produced by the deflector or sweep plates, liesin the-electron receiving surfaces of the targets or plates 54. As thebeam revolves it impinges upon the targets or plates repeatedly and insuccession to cause the emission of secondary electrons therefrom whichconstitute currents flowing to the common collector electrode or anode52. The magnitude of the current from each of the targets or plates willbe dependent, of course, upon the potentials produced upon each plate bythe corresponding individual channel coupled thereto. The secondaryelectron currents from the plates or targets fiow in succession throughthe resistance ll to cause corresponding variations in the output of theamplifier II, which constitutes a multiplexed signal current.

As illustrated in Fig. 1'7, each secondary electron current may beeffectively amplified by operating the targets or plates 54 as primarycathodes of individual electron multipliers. Each multiplier comprises aplurality of auxiliary secondary electron emitting cathodes I3 havingthe collector electrode or anode 52 as the output electrode thereof; Thetrajectories of the secondary electrons are indicated generally in Fig.17 by the arrows.

In the receiving distributor circuit illustrated in Fig. 8, the sweep ordeflector plates are maintained at a higher positive potential, forexample, twice the potential, of the first anode 44. Each target orplate 54 is connected to the cathode 35 through an individual resistanceI3 and to the collector electrode 52 through an individual seriescircuit including a condenser 12, resistance I4 and biasing battery I5.In this case the bias An input or control circuit coupled to the commontransmission channel is coupled to the oathode 35 and electrode 31across the battery 52 in series with a resistance 15. A blockingcondenser II is provided as shown. The multiplexed signal appliedbetween the cathode 35 and electrode 31 modulates the rotating electronbeam E which impinges in succession and repeatedly upon the plates ortargets 54. The secondary electron current from each target fiowsthrough the corresponding resistance I4 and produces variations in theinput of the associated amplifier II and corresponding variations in theoutput thereof.

Inasmuch as at any particular instant there is secondary electronemission from only the target or plate 54 upon which the electron beamis impinging, electron cross-talk is substantially prevented.

It will be noted that because of the form and disposition of the targetsor plates the capacitances therebetween and between each target and thecollector electrode are at substantially a minimum.

In the electronic distributor illustrated in Figs.

10 and 11, the electron gun and deflecting or' sweep plate structure isthe same as in the distributor shown in Fig. 3 and described hereinaboveexcept that the electrode 31 is provided with an integral fiange 83 towhich the supports 33 are afilxed. The targets or plates, however, areelongated parallel plates or strips I54, mounted in a substantiallycylindrical boundary coaxial with the collector electrode or anode I52,which may be an elongated rod or wire having amxed thereto or integraltherewith a metallic plate or disc 18. The targets or plates I54 aresecured to annular insulating spacers I9, for example, of mica, as bywires 80, and are supported from the stem I32 by leading-in conductorsI56 sealed in the annular flange I55. The targets or plates I54 may beconstructed of the same materials as the targets 54 in the distributorillustrated in Fig. 3 so that when the electron beam impinges upon theinner surface thereof, each target will release secondary electrons,which flow to the collector electrode I52.

The plate or disc 18 of the collector electrode structure is affixed, asby welding, to a crosspiece or support 8i which is carried by rods orwires 82 extending from a band or collar I clamped about the stem I32and having a leading-in conductor I59 connected thereto.

The electron discharge device disclosed in Figs. 1 0 and 11 isparticularly suitable for use as -a receiving distributor and may beassociated the seam cathode and the sum; electrode or anode I52 as. theoutput electrode thereof.

a cylinder of metal or other conductive material,

such for example, as graphite, and is supported by a pair ofdiametrically opposite wires or rods 85 sealed in the side wall of theenclosing vessel 2, as shown at 85, .and'extending therefrom.

As shown in Figs. 18 and 14, the targetsor plates 254, which aregenerally sectoral and which may be of any of the materials mentionedheretofore for the targets 54 in the distributor shown in 3, aresupported from an annular insulating member 81 by individual rods orwires 88, which may be encased in insulating sleeves 89, such as glasstubes. The insulating member 81 is supported by a pair of rigid rods orwires 9| having one end embedded therein and the other end afllxed to aband or collar 290 clamped about the stem 232. The insulator-targetstructure may be braced by a wire or rod 92 aflixed to one of thesupports 9| and sealed in the stem 232. Electrical connection to thetargets or plates 254 may be established through leading-in conductors256 sealed in the flange 255. The targets 254 are substantiallycoplanar, equally spaced and in cir- .cular formation about an axiscoincident with that of the collector electrode 252.

The targets or plates 254 are surrounded by conductive grid or shieldincluding a cylindrical wall 93 coaxial with the collector electrode oranode 252 and an apertured conical base having an imperforate centralportion 94 and equally spaced, radially extending tapering arms 95.- Thearms 95 form a plurality of radially extending slots 85, each of whichis in alignment with a corresponding one of ,the targets or plates 254.The grid or shield may be supported by a pair of rigid wires or rods 91secured to the supports 9|. Suittrode or anode '2 52, through the slotsor apertures 95.

In r s. and "16, whe'nxthe device is operated as a sending distributor,the-various secondaryelectron currents are modulated in; accordance withthe variable potentialsimpressed between the grid or shield 93, 95 andthe targets or plates through the transformers 58. The multiplexedsignal is transmitted to the, common transmission channel 20 by thetransformer 88.

InFlg. 15, when the apparatus is operating as a receiving distributor,the potentials corresponding to the multiplexed signal are impressedbetween the collector electrode or anode 252 and .the targets or plates254, and the components transformer I 00, and the intensity of theelectron beam is varied-accordingly. The compoable electrical connectionto, the grid or shield may be established through the conductor 92.

The electron discharge device illustrated in Figs. 12, 13 and 14 maybentilized for two-way communication as both a sending and a receivingdistributor, two ways ofoperation thereof being shown in Figs. 15 and16. In .these figures circuit elements corresponding to those of Figs.'7 ands are identified by the same numerals. The collector electrode oranode 252 is connected to the targets or plates 254 through thesecondary winding of a transformer 98 and has a positive potential, forexample of the order of 100 volts, applied thereto by a source, such asthe battery Ill. The shield or grid electrode 93 also is connected tothe plates or targets 254' as shown and is maintained at a negativepotential, for example of ten volts or less, with respect thereto by asource of such as a battery 99. The potentials applied to the variouselectrodes may be of magnitudes given heretofore in the description ofnents of the multiplex signal are distributed to the proper individualchannels. I The shield orgrid electrode 93, 95, it may be noted, servesto decrease the capacitances' be tween the targets or plates 254 and thecollector electrode or anode 252. Also, when the distributor isoperating as a sender, this electrode serves as a modulating electrode.Furthermore, the slots or apertures 96 may be of somewhat less widththan the targets or plates 254 so that but restricted portions of thelatter are energized by the electron beam.

Although several specific embodiments of this inventionhave been shownand described, it will be understood, of course, that they are butillustrative and thatvarious modifications may be madetherein withoutdeparting fromthe scope and spirit of the invention as defined in theappended claims.

- What is claimed is:

1. Signal translating apparatus comprising a collector electrode means,a plurality of spaced targets each having an electron emissive surfacefacingsaid electrode means, individual leadingin conductors for saidtargets, means for producing a beam impinging upon the emissive surfaceof said targets in sequence, and a fluorescent plate facing the oppositesurface of said targets.

2. In an electron discharge device, a cathode and an electron lenssystem in cooperativerelation with said cathode comprising a cylindricalelectrode encompassing said cathode, deflector means spaced from saidelectrode and mounted in a boundary coaxial therewith, and a secondcylindrical electrode coaxial with said first electrode, and having oneend portion extending between said deflector means and the opposite endpoorgion extending into said first cylindrical elec- 3. In an electrondischarge device, a cathode, a cylindrical electrode encompassing saidcath-' ode, an elongated cylindrical anode coaxial with said electrodeand having an end portion within said electrode, and a plurality ofdeflector plates mounted in a boundary coaxial with said anode, each ofsaid plates having an end portion and an outwardly inclined trapezoidalportion, said anode extending into the space bounded by said endportions.

4. In an electron discharge device, a cathode, an insulating memberhaving a cylindrical portion coaxial with said cathode andhaving flangesat opposite ends of said cylindrical portion, a cylindrical electrodeafllxed to one of said flanges and encompassing said cathode, deflectormeans supported from the other of said flanges and die-- stripelectrodes mounted in a cylindrical boundary encompassing said collectorelectrode, individual leading-in conductors for said strip elec trodes,each of said strip electrodes having the surface thereof toward saidcollector electrode secondary electron emissive, an electron gun forproducing an electron beam, and sweep plates for rotating said beam toimpinge upon said strip electrodes in sequence.

7. A signal translating device comprising an enclosing vessel having astem at one end, an elongated collector electrode supported from saidstem, a plurality of elongated targets parallel to said collectorelectrode and mounted in a cylindrical boundary coaxial therewith,individual leading-in conductors for said targets sealed in said stem, aplurality of spaced insulating members spacing said targets, electronbeam producing means at the other end of said vessel, and means fordirecting the electron beam to impinge upon said targets.

8. A signal translating device comprising a collector electrode, aplurality of targets in cooperative relation with said collectorelectrode, means for energizing said targets to-produce a flow ofelectrons therefrom to said collector electrode, and a shield having anapertured portion between said targets and said collector electrode.

. 9. A signal translating device comprising a plurality of radiallyextending targets arranged in a circle, a collector electrode incooperative relation with said targets, means for producing an electronbeam to energize said targets, and a shield electrode having anapertured portion betweensaid targets and said collector electrodetherewith. 11. A signal translatingdevice comprising an and having" acylindrical portion encompassing said targets. 1 4

10. A signal translating device in accordance with claim 9 whereinsaidapertured portion of said shield electrode comprises radiallyextending portions bounding radially extending apertures, one for eachof said targets and in alignment enclosingvessel having a stem at oneend, electron beam producing means at the other end of said vessel, aplurality of substantially sectoral targets adjacent said stem andarranged in a circle, an'insulating member spacing and supporting saidtargets, means supporting said member from said stem, leading-inconductors for said targets, a collector electrode mounted intermediatesaid beam producing means and said targets, and a shield electrodehaving an apertured portion between said targets and said 'collectorelectrode and a cylindrical portion encompassing said targets.

12. Means for translating signals in multiplex comprising a plurality oftarget electrodes each of which has a secondary electron emissivesurface, said target electrodes being electrically individual andseparately maintainable at desired potentials, a collector electrode inelectron receiving relation with all of said emissive surtrollablesecondary electron currents betweensaid target and collector electrodesincluding means for producing an energizing beam and means for directingsaid beam to impinge upon said target electrodes in sequence.

13. Means for translating signals in multiplex as defined in claim 12,wherein said target electrodes are electrically separate membersarranged in a circle coaxial with said collector electrode and haveindividual leading-in conductors associated therewith in such mannerthat the potential of each of said target electrodes is variableindependently of the potential of all the other target electrodes, andwherein the secondary electron producing means comprises an electron gunfor producing an electron beam and means for rotating said beam toimpinge upon said target electrodes in sequence.

FRANK GRAY.

